Internally cooled zinc condenser



Dec. 28, 1948.

E. C. HANDWERK ET AL INTERNALLY COOLED ZINC CONDENSER Filed Dec. 5, 19452 Sheets-Sheet l A xnxx-:

. INVENTORS BY ,317ml 'c/ITIHM f" ATTORNEYS Dec. 28, 1948. E.c.,HANDwERK ETAL 2,457,547

INTERNALLY COOLED ZINC CONDENSER 2 Sheets-Sheet 2 Filed Deo. 5, 1945lllllllllllllllllllll|l|l advantageously Patented Dec. 28, 1948 UNITI-:DSTATE 2,457,547 INTERNALLY COOLED ZINC CONDENSER Erwin C. Haupt,Palmerton,

Jersey Zinc Company,

C. Handwerk, Geolrge a., New York, N. Y., a corporation of New JerseyApplication T. Mahler, and Harry assignors to The New December 5, 1945,Serial No. 633,004

2 claims. (c1. 26e-15) This invention relates to condensing zinc vapor,and has for its object an improved apparatus for condensing zinc vapor.

In the customary pyrometallurgical practices of smelting zinc ores, thezinc is recovered as molten metal by condensing the zinc vapor containedin the gaseous products of the smelting operation. The condensersordinarilyl used for condensing the zinc vapor produce a considerableamount of zinc dust or blue powder which usually is returned to thesmelting operation. For example, the condensers heretofore use'd withmodern externally-heated vertical zinc retorts commonly produce bluepowder or zinc dust amounting to 7 to 15% of the output of zinc. It isordinarily necessary to recirculate this blue powder through thevertical retorts, since it is usually not in the form of salable zincdust and is difficult to melt down to liquid zinc with the use of theheretofore available equipment. A particular object of the invention isthe provision of an improved apparatus; for condensing zinc Vapordiluted with ordinary smelting gases, such as carbon monoxide and thelike, with the formation of only a minimum amount of blue powder. Theinvention is particularly adapted for use with smelting equipment ofrelatively large capacity such as modern externally-heated vertical zincretorts or electro-thermally heated retorts.

The condenser of the invention comprises a condensing chamber having azinc vapor inlet and a gas outlet and adapted to hold a body of moltenzinc. Artificial cooling means are positioned within the condensingchamber, in the path of the gaseous stream containing zinc vapor passingthrough the chamber, and a rotor within the chamber is adapted whenrotated to dip into the molten zinc and throw a substantially continuousshower of molten zinc upwardly into the chamber in the, region of theartificial cooling means. The rotor may advantageously be generallycylindrical with circumferentially spaced peripheral pockets thatsuccessively dip into the molten zinc as the rotor is rotated, such asdescribed in our copending patent application Ser. No. 626,508, liledNovember 3, 1945. The artificial cooling means is adapted to directlycool the gaseous stream containing zinc Vapor passing through thecondensing chamber, and means are provided for controlling the heatdissipated from the condensing chamber by the artificial cooling means.The artificial cooling means may be a metal shell depending into thecondensing chamber from the roof thereof, and through which a coolingmedium is circulated. The rate of flow of cooling medium through theshell may be regulated, to control the heat dissipated from thecondensing chamber, by a temperature responsive means operativelyassociated therewith and with the molten zinc in the chamber.

The foregoing and other novel features of the invention will be bestunderstood from the following description taken in conjunction with theaccompanying drawings, in which Fig. l is a longitudinal sectionalelevation of the condenser of the invention,

Fig. 2 is a transverse sectional elevation on the section line 2-2 ofFig. 1, and

Fig. 3 is a top plan View of the condenser.

The condenser of the invention as illustrated in the drawingscomprises-a generally rectangular condensing chamber 5 having a zincvapor inlet 6 approximate. one end and an exhaust or waste gas outlet 1approximate its other end. The condensing chamber is lined with suitablerefractory material and is interiorly provided with artificial coolingmeans. While the artificial cooling means may be of any suitable type,satisfactory results are secured with a bayonet water-cooler dependingfrom the roof of the chamber. As illustrated in the drawings, a metallic(e. g. iron) cooling shell 8 having water inlet and outlet pipes 9 andI0, respectively, is operatively supported in the roof of the condensingchamber, and depends into the chamber to a short distance above thenormal molten Zinc level (a) therein. The shell 8 should preferably notdip into the bath of molten zinc in the chamber, in order to avoidfreezing the zinc bath if the supply of zinc vapor should be cutoil:',or, alternatively, any portion of the shell (or cooler) thattraverses the zinc bath should be heat insulated. The portion of theshell adjacent the roof of the chamber is surrounded with heatinsulation I I zinc will not bind the shell to the roof and therebyprevent its removal.

The condensing chamber 5 communicates, beneath the lower edge of its endwall I2, with a discharge well I3 having an overflow spout I4determining the level (a) of the body of molten zinc in the condensingchamber. A collecting trough I5 receives the molten metal overflowingthe spout I4 and conveys it to casting equipment or the like. The lowerportion of the end wall I2 dips "into the molten metal between thecondensing chamber and the discharge well and seals the condensingchamber from the atmosphere at this point. The volume of molten zinc inthe condensing chamber is thus maintained subso that frozen to the boreat one end of the stantially constant by continuously withdrawing moltenzinc from the chamber as zinc vapor is condensed therein.

A generally cylindrical rotor I6 is mounted within the condensingchamber 5. The rotor is carried by a hollow or axially-bored metal shaftI1 mounted in bearings The shaft I1 is horizontally disposed and extendsthrough the side Walls of the condensing chamber between the zinc vaporinlet and the gas outlet in a direction generally transverse to thedirection of gas ow through the chamber. The rotor may be constructed ofgraphite, silicon carbide or other suitable refractory, and ,isseparated from direct contact with the shaft I1 by a sleeve I9 ofinsulating cement. The shaft I1 has a plurality of circumferentiallyspaced peripheral ribs embedded in the cement sleeve, and the bore ofthe rotor has a plurality of spaced recesses 2| lled with the cement ofthe sleeve, so that the shaft, sleeve and rotor are effectively keyedtogether. The shaft I1 is cooled by the flow of a cooling medium, suchas water, through its axial bore, the cooling medium being suppliedshaft by a pipe 22 and discharged from the other end through a pipe 23.

The peripheral surface of the rotor I6 has a plurality ofcircumferentially spaced pockets or cups 24. The shaft I1 is positionedat a level substantially above that of the molten zinc adapted to beheld in the chamber 5, and the rotor I6 is of such outside diameter thatits lowermoslt pocket is beneath the molten zinc level The rotor isrotated by means of a pulley secured to the shaft I1 and operativelyconnected to a suitable source of power, such as an electric motor (notshown).

The condenser is provided with effective seals for preventing theleakage of zinc vapor through and the freezing of molten zinc in theapertures in the side walls through which the shaft I1 extends. Thus,the rotor I6 has a laterally extending sleeve 26 at each end thereofsurrounding the cement sleeve I9 where the latter extends through thewall of the condenser. The rotating sleeves 26 extend through stationarysleeves 21. Each stationary sleeve ance with the rotating sleeve 26, andis elsewhere spaced from the rotating sleeve to provide an elongatedinner annular space 29. The outer ends of the concentric sleeves I9, 26and21 are enclosed in a gas seal comprising a tight fitting cap orhousing 3| having a gland bushing 32 through which the shaft I1 extends.A suitable non-oxidizing gas, such for example as a portion of theexhaust gas exiting from the condenser through the outlet 1, is pumpedinto the caps 3| through the inlet pipes 33 to maintain a sufficientlyhigh gas pressure within the caps to prevent zinc vapor and diluting gasfrom flowing outwardly between the stationary sleeves 21 andl therotating sleves 26.

. The sleeves 26 and 21 are so shaped that molten metal does notaccumulate in the elongated annular space 29 between the sleeves, but onthe contrary runs out by gravity into the molten zinc at the bottom ofthe condensing chamber. Thus, the ends of the stationary sleeves 21extend into annular grooves 34 in the ends of the rotor I6, and thelower portions of these ends are internally beveled or thinned to formspouts 35 for discharg ing by gravity any molten metal entering thespace 29 -between the sleeves. The annular I8 outside the condenser.`

21 has a constricted por-v tion 28, near its outer end, to provide aclose cleartion of the end of each sleeve 21 is beveled or thickened toform a backwardly sloping spout 36 for guiding any molten metal fallingon or wetting the upper surface of the sleeve towards the condenser walland thence downwardly over the sleeve to the body of molten metal.

lIn the operation of the condenser illustrated in the drawings, acontinuous stream of gas containing zinc vapor enters the condensingchamber beneath a depending baille 31 of the inlet 6, and ows in agenerally horizontal direction through the chamber and beneath adepending baille 38 to the exhaust gas outlet 1. Where the entering gasis derived from a'vertical retort smelting operation it will have atemperature of around 820 to 900 C. and will generally contain around 30to 50% zinc vapor diluted for the most part with carbon monoxide gas.Dissipation of heat from the condenser is controlled by regulating thewater, or other cooling medium, owing through the interior cooler 8, theoperating temperature within the condensing chamber being therebymaintained at about 500 to 550 C. Since the operating temperature of thecondensing chamber is indicated by the temperature of the moltenzinc inthe chamber, the articial cooling may advantageously be regulated andcontrolled by that temperature as obtained from a suitably positionedpyrometer or other temperature measuring instrument. The contemplatedcondenser temperature is preferably maintained automatically by means ofa pyrometer 39 positioned in the bath of molten condensed zinc(preferably near the discharge end of the condenser) and operativelyassociated with a valve 48 of the inlet pipe 9. The rate'of flow of thecooling medium through the cooler 8, and hence its cooling effect isautomatically controlled by the pyrometer so that the temperature of thebody of molten zinc in the condensing chamber is held within a desiredpredetermined range, thus controlling the operating temperature of thecondensing chamber.

The rotor I6 is rotated at a relatively high speed, say around 100 to150 R. P. M., clockwise as viewed in Fig. 1, so that the pockets 24 inrapid thrown laterally of molten zinc into the entering gas stream. Thepockets 24 have a generally scoop-like section with a relatively longadvancing fiat section and a shallow semi-circular depression at theinner end or bottom of the pocket. The pockets terminate short of thecircumferential peripheral ends of the rotor, so that little or nomolten zinc is against the side Walls of the condensing chamber,although the shower of molten zinc is thrown upwardly substantiallycompletely transversely of the chamber. The upwardly-directed andrapidly succeeding sheets or showers of molten zinc splash into theshower or rain of molten zinc particles falling through the chamber. andalso splash against the cooler 8, the bullies 31 and 38, and the roof ofthe chamber, with the result that the condensing chamber issubstantially filled with sheet-like showers and lmoving particles ofmolten zinc which form ideal anzu? about 5,000 B. t. u.s per minute fromth condenser, a relatively small cooler is adequate for condensing largeamounts of zinc.' Instead of the automatic control -hereinbeforedescribed, the ilow of cooling medium through the cooler may be manuallycontrolled from pyrometer readings.

Cooling of the shaft I1 permits the use of a metal shaft, and the sleeveI9 of'insulating cement inhibits appreciable cooling of the condensingchamber by the cooling medium flowing through the shaft, and eliminatesany thermal stresses in the rotor` I6. The special conflguration of thestationary sleeve 21 prevents the co1- lection and freezing of zincmetal :in .the close clearance between the sleeves 26 and 21, andconsequent stoppage of the drive shaft. The gas seals prevent theiniltration of air and the escape of zinc vapor through the 'rotatingcontact between the sleeves 26 and 21, and thus insure free relativemovement of these sleeves.

While the invention is particularly applicable to' the condensation ofzinc vapor from the gaseous products of zinc smelting operations carriedout in externally or electrically heated retorts, where the zinc vaporcontent is relatively high, itis also applicable to the condensation ofzinc vapor from larger relative amounts oi.' diluting gases. Forexample, the invention may be advantageously applied to condensing zincvapor from the gases iproduced in zinc smelting' operations carried' outin blast or cupola furnaces, where the zinc vapor 3 condensing chamberprovided with top, wall and bottom members and having a zinc vapor inletand a gas outlet and adapted to hold a body of molten zinc, a coolingshell depending into said chamber from the roof thereof, a horizontallydisposed shaft extending through the' walls of said chamber and mountedin bearings outside the chamber, means providing zinc vapor and moltenmetal seals where said shaft extends content of the gas may'be as low as2 to 5%, provided the carbon dioxide content of such gases is low enoughand if the temperature is sumlclently below the zinc dew point. In allcases,

lshowers of molten zinc throughout the entire. gas stream and thus`splashes molten zinc on the cooling means wherever located between thebames 31 and 38 above the metal bath. We claim: y L A condenser for zincvapor comprising a through the walls of the chamber, va generallycylindrical rotor having peripheral surface pockets secured to saidshaft within the chamber with the lowermost pocket beneath the levelofthe molten zinc adapted to be held in the chamber, and means forrotating said shaft so that the successively ascending pockets of therotor are caused to throw an upwardly-directed shower of molten zincinto and substantially completely transversely of the chamber in theregion of said cooling shell.

2. A condenser for zinc vapor comprising a condensing chamber providedwith top, wall and `bottom members and having a zinc vapor inlet and agas outlet and adapted to holda body of molten zinc, a cooling shelldepending into `said -chamber from the roof thereof, means forcirculating a cooling medium through said shell, a rotor provided withperipherally disposed pockets capable. when the rotor is rotated ofdipping into the body of molten zinc'and of throwing a substantiallycontinuous shower of moltenzinc upwardly and substantially completelytransversely of the chamber in the region ofsaid cooling means,and'means for rotating said rotor.

HARRY C. HAUPT.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,530,154Casparl Mar. 17, 1925 1,955,269 Anetsberger Apr. 17, 1934 2,060,070Hansgirg Nov. 10, 1936 2,091,159 Persons Aug. 24, 1937 2,117,410 YErbach May 17, 1938 2,219,826 Swinburne Oct. 29, 1940 2,288,819 NevelApr. 15, v194:1 2,348,194 Crane May 9, 1944 OTHER. REFERENCES The Chem.Age. Nov.- 4, 1944. pages 447 and 448.

